Frequency domain equalization for single-carrier broadband wireless systems
TL;DR: This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions and discusses similarities and differences of SC and OFDM systems and coexistence possibilities, and presents examples of SC-FDE performance capabilities.
Abstract: Broadband wireless access systems deployed in residential and business environments are likely to face hostile radio propagation environments, with multipath delay spread extending over tens or hundreds of bit intervals. Orthogonal frequency-division multiplex (OFDM) is a recognized multicarrier solution to combat the effects of such multipath conditions. This article surveys frequency domain equalization (FDE) applied to single-carrier (SC) modulation solutions. SC radio modems with frequency domain equalization have similar performance, efficiency, and low signal processing complexity advantages as OFDM, and in addition are less sensitive than OFDM to RF impairments such as power amplifier nonlinearities. We discuss similarities and differences of SC and OFDM systems and coexistence possibilities, and present examples of SC-FDE performance capabilities.
Citations
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Patent•
15 Sep 2006TL;DR: In this article, a radio transmitting apparatus where both a first data and a second data symbol are placed in a single block, the BER characteristic of the second data can be well maintained.
Abstract: A radio transmitting apparatus wherein when both a first data and a second data, which has a greater importance than the first data, are placed in a single block, the BER characteristic of the second data can be well maintained In this apparatus, a modulating part (101-1) modulates a first data sequence to generate a first data symbol, while a modulating part (101-2) modulates a second data sequence to generate a second data symbol A placing part (102) places both the first data symbol and the second data sequence in each of blocks constituting a single carrier signal At this moment, the placing part (102) places, in the single block, the first data at both ends of the block, while placing the second data, which has the greater importance than the first data, at the center of the block A CP adding part (103) adds, to the head of the block in which the first and second data symbols are placed, a rear end portion of that block as CP
4Â citations
01 Jan 2009
TL;DR: This thesis discusses the possibility of improving the performance of a CPSC system by exploiting the cyclic prefix for equalization purposes, and aims at using a system-based or cross-layer criterion, called goodput, for allocating resource in a coded OFDM system.
Abstract: Digital wireless communications have considerably changed not only the way people communicate, but also the way research is conducted in the field of telecommunications. In fact, the nature of the wireless medium has created a number of new challenging and fascinating research topics. In particular, a prerequisite for achieving higher and higher transmission rates in wireless systems is to develop strategies for efficiently dealing with the frequency selectivity of the wireless channel. A good candidate is the so-called cyclic prefixed block transmission, and in particular its two most popular variants which are the cyclic prefixed single-carrier (CPSC) and orthogonal frequency division multiplexing (OFDM) modulations. In this context, this thesis aims at analyzing and optimizing the use of cyclic prefixed block transmission for wireless communications. Firstly, this thesis contributes to the current state-of-the-art on the performance comparison between CPSC and OFDM, focusing on the derivation of analytical results when possible. If the channel state information is not available at the transmitter side, CPSC with minimum mean square error linear receiver is shown to achieve the best trade-off between performance and complexity, as it exploits the multipath diversity under some realistic hypotheses. Secondly, this thesis aims at using a system-based or cross-layer criterion, called goodput, for allocating resource in a coded OFDM system. Interestingly, the well-known waterfilling solution, when adequately parametrized, is proved to be near-optimal from a goodput point of view. Finally, this thesis discusses the possibility of improving the performance of a CPSC system by exploiting the cyclic prefix for equalization purposes.
4Â citations
Cites background from "Frequency domain equalization for s..."
...Consequently, as proposed in [11], a hybrid scheme could very well be considered in practice: CPSC in the uplink, and OFDM in the downlink....
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...These considerations make CPSC a good alternative candidate for the uplink [11]....
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...This is one of the reasons why CPSC was introduced in the literature [9,11] and has gained in popularity for practical implementations [49]....
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12 Nov 2007
TL;DR: In this paper, a zero padded single-carrier (SC) block transmission with minimum mean squared error-frequency domain equalization (MMSE-FDE) was proposed for impulse radio ultra-wideband (IR-UWB) systems.
Abstract: In this paper, we propose a zero padded single-carrier (SC) block transmission with minimum mean squared error-frequency domain equalization (MMSE-FDE) for impulse radio ultra-wideband (IR-UWB) systems. Moreover, the comparative study among the proposed scheme and the conventional one is presented. The proposed zero padded MMSE-FDE not only has the favorable advantages of the existing cyclic prefixed SC-FDE, but it also overcome the power loss due to the usage of the cyclic prefix. The validity of the proposed algorithm is demonstrated by simulation results with relevant discussions.
4Â citations
Patent•
24 Nov 2014
TL;DR: In this paper, a hybrid band intelligent backhaul radio (HB-IBR) is proposed, which is a combination of two radios operating in different bands, such that a common medium access control (MAC) block may be utilized between the dual radios.
Abstract: A hybrid band intelligent backhaul radio (HB-IBR) is disclosed that is a combination of two radios operating in different bands. Embodiments include a dual radio configuration wherein a first radio operates in a non-line of sight (NLOS) radio link configuration and a second ancillary radio operates in a near line of sight or line of sight configuration (n)LOS. For example, the HB-IBR may have an Intelligent Backhaul Radio (IBR) operating in the non-line of sight mode of operation within the 5.8 GHz unlicensed band, and have an ancillary radio link operating in the FCC part 101 E band of operation at 60 GHz. A common medium access control (MAC) block may be utilized between the dual radios.
4Â citations
22 May 2008
TL;DR: This paper evaluates the impact of timing offset on the transmission performance of DS-CDMA with overlap FDE by computer simulation and assumes ideal sampling timing.
Abstract: Direct sequence code division multiple access (DSCDMA) using frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion has been attracting much attention as a promising wireless access technique in a frequency-selective fading channel. The conventional FDE requires the insertion of guard interval (GI) to avoid the inter-block interference (IBI). However, GI insertion reduces the throughput. Recently, overlap FDE that requires no GI insertion was proposed. In a previous paper, we assumed ideal sampling timing. The presence of timing offset produces the inter-symbol interference (ISI) and thus degrades the transmission performance. In this paper, we evaluate the impact of timing offset on the transmission performance of DS-CDMA with overlap FDE by computer simulation.
4Â citations
Cites background or methods from "Frequency domain equalization for s..."
...The use of frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can take advantage of the channel frequency-selectivity and achieve a good bit error rate (BER) performance [4]-[6]....
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...Due to the GI insertion, the received chip block becomes a circular convolution between the transmitted Nc-chip block and the channel impulse response and therefore, IBI can be avoided [4]....
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References
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Book•
01 Jan 1986
TL;DR: In this paper, the authors propose a recursive least square adaptive filter (RLF) based on the Kalman filter, which is used as the unifying base for RLS Filters.
Abstract: Background and Overview. 1. Stochastic Processes and Models. 2. Wiener Filters. 3. Linear Prediction. 4. Method of Steepest Descent. 5. Least-Mean-Square Adaptive Filters. 6. Normalized Least-Mean-Square Adaptive Filters. 7. Transform-Domain and Sub-Band Adaptive Filters. 8. Method of Least Squares. 9. Recursive Least-Square Adaptive Filters. 10. Kalman Filters as the Unifying Bases for RLS Filters. 11. Square-Root Adaptive Filters. 12. Order-Recursive Adaptive Filters. 13. Finite-Precision Effects. 14. Tracking of Time-Varying Systems. 15. Adaptive Filters Using Infinite-Duration Impulse Response Structures. 16. Blind Deconvolution. 17. Back-Propagation Learning. Epilogue. Appendix A. Complex Variables. Appendix B. Differentiation with Respect to a Vector. Appendix C. Method of Lagrange Multipliers. Appendix D. Estimation Theory. Appendix E. Eigenanalysis. Appendix F. Rotations and Reflections. Appendix G. Complex Wishart Distribution. Glossary. Abbreviations. Principal Symbols. Bibliography. Index.
16,062Â citations
"Frequency domain equalization for s..." refers methods in this paper
...Adaptation can be done with LMS (least mean square), RLS, or least squares minimization (LS) techniques, analogous to adaptation of time domain equalizers [Hay96], [Cla98]....
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...Overlap-save or overlap-add signal processing techniques could also be used to avoid the extra overhead of the cyclic prefix [Fer85], [Hay96]....
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TL;DR: The analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel using the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel is discussed.
Abstract: This paper discusses the analysis and simulation of a technique for combating the effects of multipath propagation and cochannel interference on a narrow-band digital mobile channel. This system uses the discrete Fourier transform to orthogonally frequency multiplex many narrow subchannels, each signaling at a very low rate, into one high-rate channel. When this technique is used with pilot-based correction, the effects of flat Rayleigh fading can be reduced significantly. An improvement in signal-to-interference ratio of 6 dB can be obtained over the bursty Rayleigh channel. In addition, with each subchannel signaling at a low rate, this technique can provide added protection against delay spread. To enhance the behavior of the technique in a heavily frequency-selective environment, interpolated pilots are used. A frequency offset reference scheme is employed for the pilots to improve protection against cochannel interference.
2,627Â citations
"Frequency domain equalization for s..." refers background in this paper
...OFDM transmits multiple modulated subcarriers in parallel [ 1 ]....
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...Several variations of orthogonal frequency-division multiplexing (OFDM) have been proposed as effective anti-multipath techniques, primarily because of the favorable trade-off they offer between performance in severe multipath and signal processing complexity [ 1 ]....
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TL;DR: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered and the degradation of the bit error rate is evaluated.
Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >
1,816Â citations
TL;DR: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags.
Abstract: This correspondence describes the construction of complex codes of the form exp i \alpha_k whose discrete circular autocorrelations are zero for all nonzero lags. There is no restriction on code lengths.
1,624Â citations